A bibliometric analysis of the 100 top-cited systematic review and meta-analysis in Orthodontics

ABSTRACT Objective: This bibliometric study aimed to analyze the citation metrics, journal and author characteristics, and subject domains of the 100 top-cited Systematic Reviews (SR) and Meta-Analysis (MA) in orthodontics. Material and Methods: An electronic database search was conducted for SR and MA in the Web of Science on 16th July 2023, without language and time restrictions. Of the 802 hits returned, the 100 top-cited orthodontic articles were shortlisted. They were analyzed for citation metrics, journal characteristics (journal, year of publication, impact factor-IF), author and affiliation characteristics (number, primary and corresponding author’s affiliation, and country), study domain, and keywords. Results: These articles were published from 1996 to 2021 in 20 journals, with an impact factor of 1.9 to 10.5, by 351 researchers affiliated with 104 universities. Their citations ranged from 45 to 344, and 34 poised to be classified as classic (≥ 100 citations). The maximum number of articles was published in the American Journal of Orthodontics and Dentofacial Orthopedics (n=38), the European Journal of Orthodontics (n=18), and the Angle Orthodontist (n=8). The authors for individual papers ranged from 1 to 10, with 5 being the most common (n=58). Europe had the highest contribution regarding the number of corresponding authors, institutions, and citations. Bone anchorage and orthodontic tooth movement/Biomechanics were the most frequently researched domains (n=11 each). The most common keyword used was Orthodontics (n=19), followed by Systematic Review (n=16) and Meta-analysis (n=9). Conclusion: In general, the top cited SR and MA were published in high-impact orthodontic journals, were multi-authored, and reflected the collaborative work from different universities.


INTRODUCTION
Bibliometric analysis is a scientific computer-assisted review methodology that identifies core research characteristics by covering all the publications related to a given topic or field.
It typically measures research outputs like publication counts, citation counts, and measurements derived from these data. 1 This information is a supporting tool for decision-making in setting research priorities, tracking the evolution of science and technology, funding allocation, and rewarding scientific excellence. 2 One of the standard bibliometric methods is citation analysis, which quantifies the number and relationship of references an article receives over time. 3It also highlights the scientific progress and quality of research done throughout the years and the focus areas of active research.Despite being a time-dependent measure, it reflects the impact and progress of the research over the years, and is a widely used scientific quality indicator. 4th evidence-based clinical decision-making gaining momentum in all fields of Medicine and Dentistry, including Orthodontics, there is an increased focus on publications providing higher evidence. 5The widespread use of computer-based information systems and online access to publications have also enhanced the impact and utility of this evidence.According to the evidence-based Medicine pyramid, systematic review (SR) and meta-analysis (MA) provide the highest level of evidence, as they

MATERIAL AND METHODS
The Clarivate Analytics Web of Science (WoS) database has been widely used, being more accessible to historical literature.Therefore, a database search was performed in the WoS to track the top-cited SRs and MAs in Orthodontics.The search term in the topic field was entered as "(Systematic review OR Meta-analysis) AND Orthodont*" without any time and language restrictions.The systematic search was conducted on 16 th July 2023.The results were sorted based on the number of citations, and the first 200 articles were selected and exported to a Microsoft Excel spreadsheet (Microsoft Office 365, Microsoft Corporation, Redmond, Washington, USA), to evaluate their eligibility for inclusion in this study.
The preliminary screening of articles to assess their relevance to the study was performed independently by two authors (PV and US) based on the information from the title, abstract and the complete article, when required.Publications not directly related to orthodontics and those on craniofacial syndromes, cleft lip and palate were excluded.Any discordance related to the inclusion of a particular article was resolved by consensus discussion between all the authors.The hundred top-cited articles in the qualified list were included for data extraction and further analysis.
The information retrieved included the total number of citations, the journal of publication, year of publication, number of authors, details of the primary and corresponding authors (affiliation, Dental Press J Orthod.2024;29(2):e242401 position, and country), funding organization, the journal's impact factor (IF), Digital Object Identifier (DOI), study type and domain, and keywords. 8Manual data extraction and normalization were performed to unify terms and remove typographical errors.
Normalization was carried out for the "Author," "Organization," and "Country of Origin" fields. 10In cases of multiple and different entries for the same author, their affiliations were verified and confirmed through an internet search.Only universities and higher research centers were noted for the study's affiliation field.
Information regarding departments, private practice, and smaller centers was not considered. 8,10The orthodontic study domains were classified as proposed by Aura-Tormos et al. 11 Two investigators (MS and BN) independently collected and tabulated the data.After completion, they were compared for concurrence.A periodic team review was conducted to settle all discrepancies, and the consensus data thus obtained was treated as final.The data analysis and pictorial representation of data were developed using Microsoft Office 365 (Microsoft Corporation, Redmond, Washington, USA).

An initial keyword search yielded 802 articles. The top 200
were exported for scrutiny in descending order of the number of citations.Twenty-five articles not fulfilling the eligibility criteria regarding subject matter were eliminated during screening, leaving 175 for further consideration.From the final list, the 100 most-cited articles were included for analysis (Table 1).The systematic selection of articles is depicted in the flow chart (Fig 1).

DISCUSSION
Citation metric is a popular quantitative measure of the impact of a research article in a particular domain.Bibliometric studies analyzing various aspects of this metric and its associated factors have been a common practice in many specialties of Dentistry.In Orthodontics, scientific mapping has been conducted in many areas, like Lingual Orthodontics, 8 TAD, 9 Orthognathic Surgery, 12 and Artificial Intelligence. 13However, bibliometric studies on level one evidence articles are unavailable; to the best of our knowledge, this is the first in this regard.
Overall, the articles covered 21 subject domains.Orthodontic tooth movement/Biomechanics topped the list, with 1150 citations from 11 articles.This finding is not surprising, as this is a fundamental domain for the practice of Orthodontics.
Three of the top five domains were related to recent evolutions in Orthodontics: Bone anchorage, Digital orthodontics, and Aligners.As recent advances in any field exhibit a higher knowledge gap, evoke more interest, and instigate more research and publications, it is natural to note increasing citations of seminal publications in the domain. 14 nearly one-fourth of the articles were published in journals not exclusive to the specialty of Orthodontics, highlighting the need to go beyond specialty journals while searching for relevant content.
The scientific literature on Orthodontics is vast, and articles reaching over 100 citations are considered highly impactful and classic.It has been reported that less than 10% of the research papers fulfill the status of classic articles. 16In larger research fields, articles with more than 400 citations are considered classics.However, the classic citation varies for each field. 17In the present study, 34 articles had more than 100 citations and could be categorized as classic.This higher proportion is not surprising, since many of these publications pertain to the newer advances in the field, increasing in research and publications, and the tendency for authors to cite preferentially articles with higher levels of evidence. 18me since publication is an essential factor that impacts the citation metrics of an article. 8Older articles receive more citations than recently published ones, due to the advantage of time and the snowball effect of subsequent related articles referring to older and primary articles.The IF of a journal is another factor influencing the citation metrics, and accounts for nearly 59% of the citation discrepancy. 21 this study, top-cited SR and MA citations ranged between 45 and 344, and were published in high impact orthodontic journals.The IF of the journals included in this study ranged from 1.9 to 10.5, with a median of 3. The relationship between IF and the number of citations is bidirectional and mutually beneficial.High IF indicates high repute, visibility, and readership for the journal among peers. 22This motivates the researchers to select these journals to publish their high-quality research.
By virtue of quality, these publications inherently have a high potential for citations and boost the IF further over time.
Countries with better economic rankings are likely to publish the most impactful papers, which may be related to the availability and allocation of resources necessary to undertake such studies. 23In agreement, 21 out of 100 articles were funded in this study, most of which belonged to developed nations (Supplementary Table ).This study showed that 65 of 100 articles were from the top 10 countries in world economic rankings, based on GDP in 2023. 24Concordant with similar Dental Press J Orthod.2024;29(2):e242401 studies, 4,10,25 the majority of corresponding authors were from Europe (n=62), with the United Kingdom (n=15) and Italy (n=14) being top contributors.
Another noteworthy observation was the number of authors involved with these publications.These top 100 articles were co-authored by 351 authors affiliated with 104 universities.
The number of authors per paper varied from 1 to 10, with more than five authors in 58 publications.Further, 53 of 100 were international collaboration or multi-university research papers.These reiterate that collaboration is vital in elevating the impact of articles, and collaborative papers are expected to be more cited. 26ywords of scientific literature define the research field or topic, and enhance the visibility among peer researchers. 27It is also essential to be in words rather than phrases or sentences.Therefore, it serves as a code for locating the required article.dissertations, unpublished data, and reports, influencing the citation count.9][30] The current

25 Figure 1 :
Figure 1: Flow chart depicting the inclusion of articles.

Figure 2 : 10 Dental
Figure 2: Top 100 cited systematic review and meta-analysis in orthodontics over the years.

29 Dental
Among individual articles, the systematic review on root resorption by Weltman et al., 15 published by AJODO in 2010, topped the number of citations (n=344).This article reported high-quality evidence of risk factors associated with root resorption associated with fixed orthodontics.It should also be noted that Selvaraj M, Nivethitha B, Varshitha P, Sangeetha U, Madhan B -A bibliometric analysis of the 100 top-cited Systematic Review and Meta-analysis in Orthodontics 8,19  Correlating with other studies,19,20  more cited articles were published after 2010, highlighting the scientific expansion in Orthodontics focused on clinical trials and evidence-based practice.It is important to note that in the Cochrane Database of Systematic Reviews (IF: 8.4), an Dental Press J Orthod.2024;29(2):e242401 internationally recognized evidence-based Medicine journal, a handful of articles (n=5) were published.This might be due to the scarcity of clinical trials in Orthodontics to conduct well-designed MAs.
study may have missed articles published in non-indexed and non-English journals.The number of citations decides the impact and quality of an article; unfortunately, it could be Dental Press J Orthod.2024;29(2):e242401 time-dependent.Another shortcoming is the potential source of error in such bibliometric studies resulting from 'self-citation' 31 and 'journal bias'.The former indicates the authors' tendency to cite their publications, to improve their credentials and journal IF.Journal bias refers to the inclination of the authors to cite papers from the same journal targeted to publish their research.

Table 1 :
Top 100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 : (continuation) Top
100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 : (continuation) Top
100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 :
(continuation) Top 100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 :
(continuation) Top 100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 :
(continuation) Top 100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 :
(continuation) Top 100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 1 :
(continuation) Top 100 cited Systematic Review and Meta-analysis in Orthodontics.

Table 2 :
The 20 journals in which the top 100 cited articles published.

Table 3 :
The top-cited authors with two or more publications.

Table 3 :
(Continuation) The top-cited authors with two or more publications Selvaraj M, Nivethitha B, Varshitha P, Sangeetha U, Madhan B -A

Table 3 :
(Continuation) The top-cited authors with two or more publications Selvaraj M, Nivethitha B, Varshitha P, Sangeetha U, Madhan B -A

Table 4 :
The top 33 universities with two or more articles.

bibliometric analysis of the 100 top-cited Systematic Review and Meta-analysis in Orthodontics 26 Dental Press J Orthod. 2024;29(2):e242401 STUDY DOMAIN
The top five cited articles were mostly related to root resorption (n=344), clear aligners (n=277), OTM (n=257), digital study models (n=219), and functional appliances (n=198).With the recent advances in digital Orthodontics, aligners, and fixed functional appliances, the volume of research with citations has increased significantly.Domains like dental trauma, vertical discrepancy, and bonding and bracket removal presented least number of articles with citations.Citation analysis of journals regarding the domain bone anchorage/mini-implant (n=9) showed that these articles were most commonly published in AJODO from 2007 to 2017 (Supplementary Table).Systematic review (n=16) and Meta-analysis (n=9).Details of keywords used thrice or more are presented in Table6.Selvaraj M, Nivethitha B, Varshitha P, Sangeetha U, Madhan B -A

Table 5 :
Distribution of articles, based on research domains.

Table 6 :
Most commonly used Keywords in the top 100 cited articles.

Nivethitha B, Varshitha P, Sangeetha U, Madhan B -A bibliometric analysis of the 100 top-cited Systematic Review and Meta-analysis in Orthodontics 28 Dental
Press J Orthod.2024;29(2):e242401 17,27It is no surprise that the most often used term was Orthodontics, followed by Systematic Review and